Polymorphic variants of cytokine genes are associated with acute and chronic transplant rejection. In this technical report, the methods currently used in our centre to genotype individuals for interferon-gamma, interleukin-10, transforming growth factor-beta 1 and tumour necrosis factor-alpha are described in detail. The DNA sequences of primers and probes, and conditions for polymerase chain reactions are given, and the allele and genotype frequencies in our control populations are summarized.